TI-59 Magnetis Card difference

[Jlouis]

Hi,

I have a bunch of TI59 magnetic cards for programs that looks different from each other, one having arrows to indicated side number and other with no arrows and a darker colour.

Does anybody know the difference between them?

I searched everywhere and did not find anything.

The only difference I could find is that the one with arrows I could write and read and the other I could write, but not read.

Thanks in advance

JL